[PATCH 2 of 3] HTTP/3: proper uni stream closure detection

[Roman Arutyunyan]

On Mon, Jan 31, 2022 at 01:40:36PM +0300, Vladimir Homutov wrote:
> On Mon, Jan 31, 2022 at 10:34:07AM +0300, Roman Arutyunyan wrote:
> > # HG changeset patch
> > # User Roman Arutyunyan <arut at nginx.com>
> > # Date 1643611590 -10800
> > #      Mon Jan 31 09:46:30 2022 +0300
> > # Branch quic
> > # Node ID d3c6dea9454c48ded14b8c087dffc4dea46f78ef
> > # Parent  8dcb9908989401d750b14fe5dccf444a5485c23d
> > HTTP/3: proper uni stream closure detection.
> >
> > Previously, closure detection for server-initiated uni streams was not properly
> > implemented.  Instead, HTTP/3 code relied on QUIC code posting the read event
> > and setting rev->error when it needed to close the stream.  Then, regular
> > uni stream read handler called c->recv() and received error, which closed the
> > stream.  This was an ad-hoc solution.  If, for whatever reason, the read
> > handler was called earlier, c->recv() would return 0, which would also close
> > the stream.
> >
> > Now server-initiated uni streams have a separate read event handler for
> > tracking stream closure.  The handler calls c->recv(), which normally returns
> > 0, but may return error in case of closure.
> >
> > diff --git a/src/http/v3/ngx_http_v3_uni.c b/src/http/v3/ngx_http_v3_uni.c
> > --- a/src/http/v3/ngx_http_v3_uni.c
> > +++ b/src/http/v3/ngx_http_v3_uni.c
> > @@ -26,6 +26,7 @@ typedef struct {
> >
> >  static void ngx_http_v3_close_uni_stream(ngx_connection_t *c);
> >  static void ngx_http_v3_uni_read_handler(ngx_event_t *rev);
> > +static void ngx_http_v3_dummy_read_handler(ngx_event_t *wev);
> >  static void ngx_http_v3_dummy_write_handler(ngx_event_t *wev);
> >  static void ngx_http_v3_push_cleanup(void *data);
> >  static ngx_connection_t *ngx_http_v3_get_uni_stream(ngx_connection_t *c,
> > @@ -252,6 +253,32 @@ failed:
> >
> >
> >  static void
> > +ngx_http_v3_dummy_read_handler(ngx_event_t *rev)
> 
> should it be ngx_http_v3_uni_dummy_read_handler?

The write handler was called ngx_http_v3_dummy_write_handler.
Let's rename both of them.

> > +{
> > +    u_char             ch;
> > +    ngx_connection_t  *c;
> > +
> > +    c = rev->data;
> > +
> > +    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "http3 dummy read handler");
> > +
> > +    if (rev->ready) {
> > +        if (c->recv(c, &ch, 1) != 0) {
> > +            ngx_http_v3_finalize_connection(c, NGX_HTTP_V3_ERR_NO_ERROR, NULL);
> > +            ngx_http_v3_close_uni_stream(c);
> > +            return;
> > +        }
> > +    }
> > +
> > +    if (ngx_handle_read_event(rev, 0) != NGX_OK) {
> > +        ngx_http_v3_finalize_connection(c, NGX_HTTP_V3_ERR_INTERNAL_ERROR,
> > +                                        NULL);
> > +        ngx_http_v3_close_uni_stream(c);
> > +    }
> > +}
> > +
> > +
> > +static void
> >  ngx_http_v3_dummy_write_handler(ngx_event_t *wev)
> >  {
> >      ngx_connection_t  *c;
> > @@ -393,7 +420,7 @@ ngx_http_v3_get_uni_stream(ngx_connectio
> >
> >      sc->data = us;
> >
> > -    sc->read->handler = ngx_http_v3_uni_read_handler;
> > +    sc->read->handler = ngx_http_v3_dummy_read_handler;
> >      sc->write->handler = ngx_http_v3_dummy_write_handler;
> >
> >      if (index >= 0) {
> > @@ -409,6 +436,8 @@ ngx_http_v3_get_uni_stream(ngx_connectio
> >          goto failed;
> >      }
> >
> > +    ngx_post_event(sc->read, &ngx_posted_events);
> > +
> >      return sc;
> >
> >  failed:
> 
> Looks ok
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-- 
Roman Arutyunyan